I. Field of the Invention
This invention relates to shaft couplings, and specifically to a tapered key coupling capable of securing together for rotational movement two shafts which need not necessarily have identical diameters or identically matching keyseats. The invention has particular utility for use in machines such as tufting or other textile machines where the shaft couplings are used in relatively inaccessible areas where precise alignment of coupled members must be possible, yet with easy assembly and disassembly capability.
II. Description of the Prior Art
Conventional couplings for driving one shaft by another shaft for the most part rely on having identically machined slots or keyseats on the ends of the shafts to be joined. Complicated arrangements including as many as five keys inserted into the slots or keyways have been known, each succeeding key forming an ever narrower wedge. This is a time consuming process, and with certain given conditions it may be possible to realign the shafts precisely.
Another significant problem related to the first is the time consuming process of precisely aligning or realigning the shafts to be coupled. This process becomes even more complicated when multiple keys are utilized.
A third significant problem with conventional keyed couplings is that the maximum torque is applied to the outermost edge of the keyway, rather than having the driving load distributed over the inner surface of the keyway. This results in the outer edges of the keyway becoming rolled, and eventually renders the keyway unusable.
It has been suggested, for example in U.S. Pat. No. 3,236,572, to utilize a split hub or collar for securing the collar onto a shaft without disrupting the surface of the shaft by causing burrs. However, this teaching does not meet the problem of joining two shafts which may possibly have different diameters and which almost certainly have non-identical keyseats or slots.
Further, the teaching of aforementioned U.S. Pat. No. 3,236,572 also relies upon a removable key, a particular inconvenience avoided in the coupling of the present invention, and also makes no provision for precisely aligning coupled shafts.